The present invention relates to an apparatus for producing a corrugated tube from a smooth walled starting tube, which comprises clamping elements for fluidtightly engaging opposite ends of the starting tube, means for feeding a hydraulic pressure fluid into, respectively out of, the starting tube, split corrugation forming discs, and an hydraulically operated offsetting unit to axially compress the starting tube under simultaneous axial movement of the corrugation forming discs.
Such an apparatus is for instance known from the German Pat. No. 20 59 812. The deformation of the starting tube is thereby carried out in horizontal position of the latter. A carriage movable on the machine frame in upsetting direction is provided for this purpose, in which the carriage is provided with a head, tiltable about a vertical axis, with a horizontally extending hollow receiving mandrel for the starting tube and the corrugation forming discs mounted thereon.
To place the starting tube and the corrugation forming discs onto the mandrel, the latter has to be tilted from the offsetting direction to a position substantially normal thereto. In this position an intermediate member and subsequently thereto the smooth walled starting tube is moved by hand onto the receiving mandrel until the front end of the starting tube passes through a seal at the head and engages an abutment face of the latter. Subsequently thereto to split corrugation forming discs are individually, one after the other, placed against the outer circumference of the starting tube and connected with each other. Thereafter a comb-shaped distance holding member for maintaining the corrugation forming discs axially spaced from each other is placed against the latter and subsequently thereto an additional intermediate member is placed on the receiving mandrel. After all of these elements are placed on the receiving mandrel, the latter is tilted back to the offsetting position.
By actuating an offsetting unit, formed by a hydraulically operated cylinder and piston unit, the carriage is now moved in axial direction until the free end of the receiving mandrel engages into a pressure fluid housing and the corresponding end of the starting tube passes through a seal in a chamber formed in the pressure fluid housing. The starting tube is thereby clamped between an abutting face in this chamber and the aforementioned abutting face.
Pressure fluid is then fed over the pressure fluid housing into the receiving mandrel and over bores in the wall of the latter into the starting tube. The pressure of the hydraulic fluid is chosen in such a manner that the wall of the starting tube bulges outwardly between the corrugation forming discs so that the latter may not shift in axial direction.
At this moment the distance holding member may again be removed. By subsequent actuating the offsetting unit while maintaining fluid pressure in the interior of the starting tube, the starting tube will be axially offset so as to form corrugations between successive corrugation forming discs.
After the corrugation forming discs abut against each other, the formation of the corrugations in the starting tube is finished. The pressure fluid is subsequently thereto discharged from the finished corrugated tube and the offsetting unit is returned to its starting position. Subsequently thereto the carriage is returned to its starting position, the receiving mandrel is again tilted through 90.degree. out of its offsetting position and only subsequent thereto it is possible to remove the corrugation forming discs, the intermediate members and the finished corrugated tube individually, one after the other, by hand from the receiving mandrel.
It is obvious that the production of corrugated tubes with this known apparatus is extremely cumbersome since not only a great number of manually carried-through operations are necessary but also, due to these manual operations, there will arise a great number of idle periods therebetween in which no corrugations are formed.